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      <title>Kafa 中如何保证顺序消费 - 交互式测验</title>
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          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Kafa 中如何保证顺序消费 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
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      <script>
        const quizData = [
  {
    "question": "根据文档，在Kafka中实现顺序消费的根本前提是什么？",
    "options": [
      "所有消息都必须发送到同一个Topic中。",
      "消费者必须使用多线程并发处理消息以提高效率。",
      "将需要保证顺序的消息发送到同一个分区，并确保该分区在同一时间只被一个消费者消费。",
      "生产者在发送消息时为每条消息附加一个全局唯一的序列号。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档的核心思想是，Kafka本身只保证分区内的消息有序。因此，要实现业务上的顺序消费，必须首先通过分区策略（如使用自定义分区器）将关联消息路由到同一分区，然后在消费端确保一个分区只被一个消费者实例处理，这样就能完整地利用Kafka提供的分区内有序性。",
    "source": "文档中「Kafa 中如何保证顺序消费」和「分区设计」部分",
    "hint": "文档开篇就总结了实现顺序消费的核心依赖：“通过将相关数据发送到同一个分区，以及每个分区只分配给一个消费者来消费...”"
  },
  {
    "question": "在生产者端，为了确保一组相关的消息（例如，同一个订单的更新事件）能够被顺序消费，最关键的操作是什么？",
    "options": [
      "为每条消息设置相同的消息键（message key）。",
      "提高生产者的发送速率。",
      "将消息均匀地发送到Topic下的所有分区中。",
      "使用自定义分区器，确保相关消息被路由到同一个分区。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档在“分区设计”部分明确指出，生产者可以通过自定义分区器来控制消息的分发逻辑。为了保证顺序，需要将具有业务关联性的消息（如同一订单ID的所有操作）稳定地发送到同一个分区。使用消息键是实现这一目标的常用方法，但更根本的机制是分区器的逻辑。",
    "source": "文档中「分区设计」部分",
    "hint": "思考一下生产者如何决定一条消息应该进入哪个分区。文档中提到了一个具体的组件来控制这个行为。"
  },
  {
    "question": "如果一个消费者组内的消费者数量大于其订阅的Topic的分区数量，会发生什么情况？",
    "options": [
      "Kafka会自动增加分区数量以匹配消费者数量。",
      "多个消费者会同时从同一个分区读取数据，导致顺序错乱。",
      "一部分消费者将会处于空闲（idle）状态，因为没有分区可以分配给它们。",
      "系统会抛出异常并停止所有消费者的工作。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "Kafka的设计原则是：在一个消费者组内，一个分区最多只能被一个消费者实例消费。当消费者数量超过分区数量时，多余的消费者将无法被分配到任何分区，因此它们会保持空闲，等待其他消费者退出后进行再均衡（rebalance）。",
    "source": "文档中「分区数与消费者数的关系」和「消费者组配置」部分",
    "hint": "文档提到“需要确保消费者数量不超过分区数量”。思考一下如果违反了这个建议，Kafka的分配机制会如何处理“多余”的消费者。"
  },
  {
    "question": "在消费者端，为了保证从单个分区获取的消息被严格按顺序处理，文档推荐了哪种消息处理方式？",
    "options": [
      "使用异步回调机制处理每条消息。",
      "将收到的消息放入一个并发队列，由多个工作线程并行处理。",
      "使用单线程处理消息，或者采用同步处理方式，处理完一条再处理下一条。",
      "根据消息的时间戳进行排序后再处理。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档在“消息处理逻辑”部分强调，即使从分区中按顺序拉取了消息，如果消费端的处理逻辑是并发的，也可能导致处理顺序的错乱。因此，为了维持严格的顺序，推荐采用单线程或同步的方式，确保消息按其在分区中的顺序被逐一处理。",
    "source": "文档中「消息处理逻辑」部分",
    "hint": "文档明确对比了两种处理方式：“应该按照分区顺序逐条处理消息，而不是并发处理消息。”"
  },
  {
    "question": "关于偏移量（Offset）的管理，为了在发生故障后能准确恢复消费并保证数据一致性，文档推荐了哪种提交方式？",
    "options": [
      "开启自动提交（auto-commit）并设置一个极短的提交间隔。",
      "在处理消息之前立即提交偏移量，以防止消息重复。",
      "采用手动提交，并在消息被完全、成功处理之后，再同步提交偏移量。",
      "将偏移量存储在外部的数据库中，完全不使用Kafka的提交机制。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档在“提交偏移量的管理”部分指出，手动提交偏移量能让消费者精确控制提交流程。在消息成功处理后再提交，可以避免因处理失败而导致消息丢失。采用同步提交则能确保偏移量成功写入Kafka后才继续处理下一条消息，为系统提供了更强的可靠性保障，防止在故障时出现重复消费或消息丢失的问题。",
    "source": "文档中「提交偏移量的管理」部分",
    "hint": "思考一下，在“处理消息”和“提交偏移量”这两个操作之间发生崩溃，哪种策略能更好地保证“至少一次”或“精确一次”的消费语义？"
  },
  {
    "question": "根据文档，以下哪项配置组合最能确保Kafka的顺序消费？",
    "options": [
      "生产者随机分区，消费者多线程处理，自动提交偏移量。",
      "生产者按Key分区，消费者单线程处理，处理完消息后手动同步提交偏移量。",
      "生产者轮询分区，消费者单线程处理，处理消息前手动提交偏移量。",
      "生产者按Key分区，消费者数量大于分区数，自动提交偏移量。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "这个选项整合了文档中提到的所有最佳实践：1) 生产者按Key分区（一种实现“相关消息到同一分区”的方式）；2) 消费者单线程处理（保证处理逻辑的顺序性）；3) 处理完消息后手动同步提交偏移量（保证消费状态的可靠性和一致性）。其他选项都包含了至少一个与文档建议相悖的操作。",
    "source": "文档中「分区设计」、「消息处理逻辑」和「提交偏移量的管理」部分的综合理解",
    "hint": "将文档中提到的生产者、消费者处理逻辑和偏移量管理三个方面的最佳实践结合起来，就能找到最完整的答案。"
  }
];
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            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
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            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

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                '<h2>答题报告</h2>' +
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                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
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                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
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                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
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                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
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                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  